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<a name="Flonums"></a>
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<a name="Flonums-1"></a>
<h4 class="subsubsection">3.6.2.3 Flonums</h4>
<a name="index-flonums"></a>
<a name="index-floating-point-numbers"></a>
<a name="index-constants_002c-floating-point"></a>

<a name="index-precision_002c-floating-point"></a>
<p>A <em>flonum</em> represents a floating point number.  The translation is
indirect: a decimal floating point number from the text is converted by
<code>as</code> to a generic binary floating point number of more than
sufficient precision.  This generic floating point number is converted
to a particular computer&rsquo;s floating point format (or formats) by a
portion of <code>as</code> specialized to that computer.
</p>
<p>A flonum is written by writing (in order)
</p><ul>
<li> The digit &lsquo;<samp>0</samp>&rsquo;.
(&lsquo;<samp>0</samp>&rsquo; is optional on the HPPA.)

</li><li> A letter, to tell <code>as</code> the rest of the number is a flonum.
<kbd>e</kbd> is recommended.  Case is not important.

<p>On the H8/300, Renesas / SuperH SH,
and AMD 29K architectures, the letter must be
one of the letters &lsquo;<samp>DFPRSX</samp>&rsquo; (in upper or lower case).
</p>
<p>On the ARC, the letter must be one of the letters &lsquo;<samp>DFRS</samp>&rsquo;
(in upper or lower case).
</p>
<p>On the Intel 960 architecture, the letter must be
one of the letters &lsquo;<samp>DFT</samp>&rsquo; (in upper or lower case).
</p>
<p>On the HPPA architecture, the letter must be &lsquo;<samp>E</samp>&rsquo; (upper case only).
</p>
</li><li> An optional sign: either &lsquo;<samp>+</samp>&rsquo; or &lsquo;<samp>-</samp>&rsquo;.

</li><li> An optional <em>integer part</em>: zero or more decimal digits.

</li><li> An optional <em>fractional part</em>: &lsquo;<samp>.</samp>&rsquo; followed by zero
or more decimal digits.

</li><li> An optional exponent, consisting of:

<ul>
<li> An &lsquo;<samp>E</samp>&rsquo; or &lsquo;<samp>e</samp>&rsquo;.
</li><li> Optional sign: either &lsquo;<samp>+</samp>&rsquo; or &lsquo;<samp>-</samp>&rsquo;.
</li><li> One or more decimal digits.
</li></ul>

</li></ul>

<p>At least one of the integer part or the fractional part must be
present.  The floating point number has the usual base-10 value.
</p>
<p><code>as</code> does all processing using integers.  Flonums are computed
independently of any floating point hardware in the computer running
<code>as</code>.
</p>

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